Rules of engagement
by FrankieQuinn13
Summary: A few years ago, James made a promise. Slash marauders era


**A/N: yeah.**

 **Marauders era AU**

 **Apologies spelling grammar and OOCness**

 **Disclaimer: I do not own Harry Potter or any of its characters**

James kept his eyes up ahead as he absently stirred the potion that he and Sirius have been working on for the past sixty minutes. Letting his gaze drop for a brief moment to check on the potion, James briefly noted that the color didn't seem quite right since it was meant to be a bright forest green and not the dark murky moss green that he had stirring in his own cauldron but he didn't particularly care either, not really anyway.

He might not be brilliant at potions but he did well enough to at least pass the class, so he wasn't too worried about the end results, although he knew that his parents certainly were. They'd be more than happy if James actually started putting a little bit more effort into his potions work since it was essentially his worst subject.

But James lacked the motivation to try harder, Potions is terribly boring and in his opinion unnecessarily complicated, he never quite understood what students like Evans and Snape found so fascinating about it. Of course, he was capable of being motivated into doing better, provided he had the right person there to do said motivating.

Someone with beautiful eyes and a wicked tongue, someone brilliant at potions and basically every other subject in school someone who normally wouldn't give him the time of day.

James held back a sigh as he stared at the two at the desk at the front of the class the way he's been doing since the first half of their double period started in the first place. Lily Evans stood by Severus Snape's side, dutifully preparing the potions ingredients to the Slytherin's specifications while Snape kept his eye on the watch hanging on the wall in the potions classroom, making sure that each one was put in at the exact time that it was meant to be added while stirring clockwise once before stirring counter clock wise three times. James only briefly noted that their procedure of preparing the potion differed vastly from the way that he and Sirius were doing it, but that thought only lasted a moment as the Gryffindor chaser let out a wistful sigh and kept his eyes on the two as they worked.

Anyone that turned back to look at him might have thought that he was staring at Lily Evans as the girl flicked her long hair back over her shoulder, causing the bright red curls to rise and fall onto her back in a curtain of bright flames before the girl gave her potions partner that sweet beautiful smile and her emerald eyes sparkled when he told her to add the next potions ingredient. The muggle born witch is stunningly beautiful after all, smart and talented, plus with James constantly hounding the girl in his attempts at getting her to go out with him it seemed like the most logical and probable reason for James to be staring so intensely in that particular direction.

Unfortunately the truth wasn't quite so logical or even the slightest bit probable.

James only briefly registered his potion begin to change color as he continued to watch the two. They always worked together during potions, despite the inherent dislike or rather hatred that existed between the two houses; they were best friends after all. They've been best friends for as long as James can remember, ever since that first train ride to Hogwarts. Lily's friends and most of Gryffindor house wasn't too fond of their relationship but the auburn haired girl wouldn't be deterred from spending time with her friend, so eventually they left her be deciding that it would be her own fault should something inevitably go wrong and she be left heartbroken. But Lily didn't care and for the most part Snape didn't seem to mind the girls company, in fact it seemed that he reveled in it. Unfortunately things weren't so easy for him. He didn't have many friends in his own house, being a half blood he was already at a disadvantage when faced with some of the more ruthless, bigoted members of his house so he couldn't be as open about his affections for Lily as she was.

Luckily the Gryffindor/Slytherin potions class was uneven resulting in at least one Slytherin and one Gryffindor being required to partner up during class, so Severus could get away with spending the time with his best friend and then he could always count on Lucius Malfoy's support whenever he wanted to spend time with Lily after class. Malfoy didn't particularly like Evans… at all, what with her being a muggleborn witch from the lion's den and all, but he liked Severus and as loath as he was to admit it nothing made Snape happier than when he got to spend time with the girl so he'd help out whenever it was necessary. Intervene whenever one of the snakes got a little twitchy at the sight of the two together and allowing the girl to slip into the Slytherin boys' dorm rooms so she could see Severus every now and then. They might be in rival houses but they'll never let anything get between them and James envied that.

He envied the fact that Evans could walk right up to Snape and talk to him like it was the most normal thing in the world, smile and laugh with him or maybe even hold his hand. James felt something in his chest give a particularly painful tug at the memory of the two sitting beneath the great oak by the lake one summer afternoon, with Lily's head resting on his shoulder while her arm stayed wrapped tightly around his own.

He remembers the anger he felt that day, surging through him like a bolt of electricity as he and Sirius approached them while Remus and Peter trailed on after them a few feet behind. James couldn't explain exactly what he was thinking when he saw them like that but the image just had him seeing red and he moved and spoke without even really thinking about it. Luckily James snapped out of it the moment that Malfoy's annoyed drawl reached his ears and the prefect immediately put a stop to the show. James snapped out of it just in time to realize that a crowd had gathered around them and Severus was hanging upside down in the air with James' hands on his exposed belt buckle. The raven flushed horribly at his newfound position and looked to Sirius who seemed to be turning a similar shade of red as he immediately let go of Snape's shirt which he was apparently right in the middle of unbuttoning and James did the same.

Malfoy gave them both detention, making sure to glare at Remus as he promised to inform Professor McGonagall about his lack of intervention in a clearly volatile situation before reversing the charm that they cast on Snape. The raven haired Slytherin hit the ground hard before Evans rushed to help him and took him to the infirmary while some of the students watching the scene snickered and laughed. Severus' expression was filled with mortification and he almost seemed to hold Evan's hand a little tighter as he was helped away and right at that moment James hated himself with every fiber of his being.

He hated that look, right then James wanted nothing more than to reach out and comfort the Slytherin, apologize a thousand times over and make sure that Snape was never hurt by him or anyone else ever again. But he couldn't.

Not just because Snape probably wouldn't let him within five feet of him without hexing him into oblivion for what he did that day and every other day since they first met on the train, not just because house loyalties dictated that he would be a traitor if he so much as attempted to console the other boy and not just because his reputation would be forever ruined if he so much as thought of approaching Snape that way. But because he promised.

Two years ago while they spent detention with Slughorn, James made a promise and as much as it pains him to do it, as much as everything in the hazel eyed wizard screamed for him to do otherwise, James wouldn't break that oath. He couldn't break that oath, the mere thought is unimaginable…

Alright so maybe James could imagine breaking it, but he wouldn't, he's a man of his word after all he can't betray a friend's trust like that.

No matter how much he wanted to. Even if Severus was worth the betrayal, sweet Merlin was he worth it, James couldn't give in, he won't give in.

Yes, contrary to popular belief James fancies Severus.

Bugger that, James loves Severus, always has.

Ever since they met that first day on the train, James just knew that Severus was something special. Of course he certainly noticed Lily Evans with her long red hair and her emerald green eyes; Lily was beautiful but Severus…

There was just something about him, a secret that lay hidden somewhere beneath the mask he wore and those never ending dark eyes. The fact that Severus hadn't even thought twice about blatantly insulting James mere moments after they met did nothing to deter the boy's fascination; in fact it only seemed to encourage it.

James was admittedly a bit of a spoilt brat, so when someone actually blatantly denied him, insulted him, outright rejected him it immediately grabbed his attention.

He wasn't able to stop thinking about the other boy after that, even after they were sorted into opposing houses, he watched Severus across the Great Hall during dinner and as the prefects led all the first years to their respective houses. He thought about the next time that he'd see Severus, how he'd show the other boy that he wasn't the dunderheaded twit he clearly thought James to be and how he'd surely have the other boy's attention for the rest of their years at school. It didn't matter that Severus was in Slytherin and he was in Gryffindor or that he seemed more interested in the redheaded girl he sat with on the train than he was in James, none of it really mattered not until they reached the dorm rooms at least.

James made a promise and he intended on keeping his promise, regardless of how much it pained him to do so.

Just then Snape brushed back a greasy lock of hair back behind his ear before gesturing to the girl beside him to add the next ingredient as he continued to stir. James knew, despite all the jokes and taunts he constantly spewed at the Slytherin that his hair wasn't always like that. It only got greasy after they finished a potion in class or after Severus finished helping Slughorn with one of his projects after class. It would seem something in the fumes coming from the numerous potions ingredients that Severus brewed didn't agree with his hair so it would always come out looking greasy afterwards.

Sometimes James would wonder if there wasn't a way to stop his hair from reacting to the fumes, maybe a potion that could be made to help Severus improve his situation because in all honesty James loved Severus' hair. The way the Slytherin would let it fall over his eyes to cover his face almost always made him itch with the sudden urge to reach out and brush it behind his ear, let his hands tangle in those ink black locks before leaning in for a sweet kiss. Of course James wouldn't mind helping Severus tend to his hair if he ever got the chance, he can see it all play out in his mind. In a bath tub or maybe in the shower James would offer to wash his hair and Severus would let him. He could almost feel Severus lean back against him as he let out a soft moan while the soap bubbles washed away in the drain beneath their feet, feel the smooth wet glide of skin against skin as he felt Severus' warm body press against his own. The clean scent of just Severus as he leaned down to kiss along the Slytherin's jaw while his mouth fell open to let out soft panting breaths.

The hazel eyed wizard let out another wistful sigh as he kept his eyes up ahead, wishing for what surely wouldn't be the last time that he could just give up the charade and finally take what he's wanted for so long when his best mate suddenly interrupted his thought.

"Drooling over Evans again, are we?" Sirius asked as he added the powdered doxy shells to the potion before he got started on preparing the fluxweed. "You remember that she's already agreed to go out with you right? You don't need to keep harassing her anymore."

James almost frowned at his friend in confusion when he suddenly remembered that he was indeed officially dating Lily Evans, or rather Lily's officially agreed to spend more time with him since he's stopped picking on her best friend and seemed to be maturing at least a little. In all honesty James wasn't sure what he was doing with Evans, at first when he'd started pursuing her it was mainly because she spent so much time around Severus, therefore meaning that if she finally agreed to be his girlfriend, James would be spending all that time around Severus without drawing too much attention to himself. But he had to keep up appearances, so he'd prank the Slytherin and tease him, if only so the other houses didn't become suspicious. But now that he's sort of dating Lily he's found that he finally had a reason to stop hurting the one he loves since everyone thought he was only doing it to impress the red haired girl.

Of course he's attracted to Lily and in all honesty he could definitely see himself married and starting a family with the girl, so he can't honestly say that he hates having her as his girlfriend but he also knew that he'd be over the moon if he had Severus in her place instead.

But then again it would probably be a cold day in hell before Severus so much as gave him the time of day.

James rolled his eyes, "Haha, hurry up and add the fluxweed. I'm pretty sure we're ten steps behind everyone else and I don't want to have to stay after classes just so we can finish."

Sirius finished slicing the plant before adding it to the potion but the color still hadn't seemed to change, James stared down at it for a moment, briefly wondering if there would be anyway of salvaging it, but he had no idea if there was. Severus would probably know, hell Severus could probably brew this potion backwards with his eyes shut if he really wanted to and at that moment James resisted the urge to sigh all over again when Sirius suddenly spoke, drawing his attention.

"James, can I ask you something?"

James blinked at that but kept stirring the potion even as he answered, "Sure Padfoot, what is it?"

Sirius hesitated for a moment and James couldn't help but look up and frown since he could both feel and see the hesitation in his eyes before he spoke, "You like Evans right? I mean, you really fancy her? This isn't just some phase you're going through, you're serious about her?"

James almost bristled at the insinuation. Sure he wasn't usually one for commitment since his dating escapades consisted of him going through each house, not really sure where the first girl ended and the next one began, but that was just because he couldn't have what he really wanted. In all honesty, James was a terrible romantic and he truly believed in giving your heart to just one person and only one person for the rest of your life. The girls in the past never really counted because he never actually loved any of them. How could he when he was already in love with Severus; but they proved to be good enough to at least distract him from the person that he really wanted, the person he desired above all else. Lily however was different, yes James was using her as a distraction as well, but she was different because Severus loved her more than anyone else in this world, so of course he'd never dream of hurting her and stringing her along. Hurting her would be the same as hurting Severus and James never wanted to do that ever again.

"Of course I am! Why on earth would you think-"

"It's not that I think you're just playing with her James it's just." Sirius paused for a moment in preparing the next ingredient as he took a deep breath before he finished, "Well now that you're with Evans, you won't need anyone else, so it would be fine if I went after Severus right?"

James froze, "What?"

Sirius sighed as he started chopping the bloodroot, "I was thinking, since you're with Evans now, you wouldn't be so interested in Severus anymore and it would be alright if I tried dating him, once I get him to actually agree to it of course, but you managed to soften Evans up so I think I have a shot at-"

"No."

Sirius froze as well, "What?"

"I said no, Sirius." James answered coldly letting go of the ladle in the cauldron, "We had a deal remember, we both promised, since we both fancied him neither of us would go out with him."

Yes they did.

In first year, just after they were sorted into their respective dorm rooms; Sirius, James Peter and even Remus were still brimming with excitement since they were officially spending their first night at Hogwarts. They spoke of all the different classes they were looking forward to, the professors they wanted to meet, joining the Quidditch team once they were old enough and a few pranks that they could play on their house mates and other students from the other houses. Eventually though, James and Sirius started talking about the two that they met on the train, while Peter snored and Remus listened intently. Sirius told James how disappointed he was that the dark haired boy was sorted into Slytherin since he probably would've stayed with them if he'd been sorted into Gryffindor, it was then that James teasingly asked if Sirius liked the boy only to frown when he got nothing but silence and a bright scarlet blush for an answer.

They didn't discuss that particular subject again till third year, after the incident at the lake. McGonagall had them both sent to Slughorn and they were set to scrubbing potions instruments for the rest of the night when Sirius suddenly brought it up. He admitted to what he was thinking when they had Severus up hanging in midair. He told James how the crowd almost seemed to melt away when Severus' shirt start to slip to reveal the teen's stomach, how the smooth soft skin almost seemed to call to him and he couldn't help but touch it before suddenly wanting to feel more of it, maybe even taste it. James admitted that he hated seeing Severus with Lily so he just moved without thinking, just determined to do all he could to prove to Severus and everyone else who he belonged to, who he should've been with. It occurred to both of them right then and there that they fancied Snape and since neither one of them has ever really liked the idea of sharing, they also became very much aware of the fact that their feelings for the Slytherin were essentially a threat to their friendship so they agreed right there and then, they made a pact.

Since they both liked Severus, they'd both stay away from him, since one would hurt the other if they tried and James was determined to keep that promise because quite frankly as much as he loved Sirius like a brother, if he couldn't have Severus then no one could, not even Padfoot.

"I don't see how that matters now." Sirius said folding his arms across his chest, "You have Lily Evans now remember, the same Evans you've been chasing after for the past three years."

James growled in annoyance, "I was only chasing after her because I promised you that I wouldn't go after Severus."

"Is she just a replacement? I thought you said you were serious about her."

"I am serious about her, I wouldn't hurt Lily and you know that."

"Then what, do you want both of them to yourself?" Sirius asked in disbelief before giving a scoff, "Newsflash for the spoilt Potter prince. You can't have your cake and eat it too. You have Evans, it's not fair of you to want to try and string Severus along too."

"That's not what I'm trying to do."

"Then what are you trying to do?"

"Nothing!" James growled in frustration, "We had a deal, you stay away from Severus, then I stay away from Severus. My dating Evans has nothing to do with the promise we made. If I hadn't made that promise I would've gone after him not her and you know it."

"Yeah well you're dating Evans now, so I don't see how that deal still matters. It's not like you'd break up with her just so you could try and go after Severus if I called the it off anyway so-" Sirius paused at the look he saw in his best friends eyes and he almost gaped. "Oh you can't be serious! You'd actually leave her if-"

"Wouldn't you?"

James asked with an arched brow and Sirius paused before trying to speak, only for no words to come out no matter how many times he opened and closed his mouth. The animagus just gave a frustrated sigh as he sputtered out, "That's beside the point. I'm not the one with the girlfriend here, you are."

The potion in front of them began to bubble suspiciously. Now would be the time to add the next ingredient since the next ingredient would help the potion reduce its heat and neutralize any explosive qualities caused by the doxy shells.

However at that present moment in time, James and Sirius were just a bit preoccupied.

"A girlfriend I only have because-" James cut himself off as he took a deep breath to finally turn back towards the potion, "You know what Padfoot just let it go, we're not calling off the deal. It's not like Severus would ever give you the time of day anyway."

James looked down at the potion and frowned when he found it to be much darker and murkier purple.

What on earth?

"And what's that supposed to mean?" Sirius asked incredulously and James just rolled his eyes at his friend, "Oh be honest Sirius, do you really think Snape would let you anywhere near him after everything that you've done."

Sirius blinked in shock, "Everything _I've_ done?!" the brunette glared a she stepped closer to his friend, "I think your forgetting your involvement in _everything I've done_ Prongs. You've… meddled with Severus just as much as I have." Sirius said, unwilling to admit that it was more like they've been torturing Snape for the past few years and weren't just meddling. The idea that Severus hated either of them for good reason was just too much to think about right at that moment. "You took away his best friend."

"I wasn't the one that tried to him kill last year." James hissed out with a glare only for his eyes to widen at the same time as Sirius' at the words that left his mouth and the hazel eyed wizard was about to take it back and apologize when-

"Mr. Potter and Mr-what in Merlin's name are you doing?!" they suddenly heard Slughorn shout causing both to turn towards the front of the class only to see dark smoke rising from their cauldron while the dark purple liquid inside started to glow as it bubbled over spilling all over the cauldron's copper sides and dripping dangerously close to the flame beneath.

Both caught sight of Severus a few tables ahead, who had turned towards them only for his eyes to go the widest that either has ever seen them as he immediately grabbed Lily's hand and made for the door. James' eyes went wider than before and Sirius couldn't help but curse, "Oh shit."

"EVERYONE OUT RIGHT NOW!" The students scattered with some screaming as they hurried out of the room but James and Sirius weren't fast enough before the potion exploded with a resounding boom.

It wasn't till the next day that they both woke up in the hospital wing, both heavily wounded but thankfully still alive with about eighty percent of their bodies covered in gauze and whatever horrible potion Madame Pomfrey put on their burn wounds to help them heal quicker. The woman had scolded both of them for longer than James cares to note, telling them how reckless and irresponsible they were before Dumbledore came in to inform them of their punishments.

Luckily James and Sirius got the worst of it with only a handful of students getting burnt here and there but otherwise there wasn't too much damage done, so they'd only have about a month's worth of detention.

It was right after the head master left and the medi witch went off to see to some other patient who was resting behind one of the curtained beds on the other side of the room that Sirius suddenly spoke.

They were both restrained, with their limbs suspended above the bed with the use of a levitation spell since Pomfrey wanted to avoid aggravating their wounds any more than they were so James couldn't really do more than turn his head so he was looking at his best friend as he spoke.

"Do you think Severus got out alright?"

James gave a snort, "He got out the moment he saw the potion he's probably fine."

Sirius said nothing as he stared up at the ceiling and James sighed, "Look mate, I'm sorry about what I said before. I-I know you never meant to hurt him last year, things just got out of hand-"

"He's just so frustrating you know." Sirius said with his eyebrows pulling together in a tight line, "I just wanted to get him rattled, get some kind of reaction out of him I was going to get him out before anything happened I swear but then he went there early and… you saved him."

James felt himself flush a bit at the memory, remembering how Severus had clung to him after they made it out of the Shrieking shack and back to safety how he could just hold the teen for a whole blissful moment without fear of being hexed or cursed before Snape suddenly seemed to remember himself and all hell broke loose.

Merlin, he really is frustrating.

"He really does hate me doesn't he?"

James tried for a smile, "If it makes you feel any better he probably hates me just as much as he hates you."

Sirius gave a snort, "At least you still have Evans to fall back on."

"You're hardly one to talk with all those girls you date."

"That's different."

"Different how?"

"They aren't Snape."

James let out a sigh, "Neither is Lily."

Sirius turned his head towards his friend, "I'm sorry about what I said too and I suppose, I just thought that since you started dating Evans you were over him."

"Well, it wasn't fair of me to try and hold onto him while I'm with her. Can't have everything I want can I?" Sirius laughed as he looked back up at the ceiling, when James spoke again, "Do you think I should break up with Lily?"

Sirius frowned, "What on earth for?"

James blushed and Sirius let out a heavy sigh, "Oh you have got to be kidding me? What happened to sticking to the promise?"

"Well I was thinking, it might not be so bad sharing Snape, as long as it was just with you." James said that last part quickly when Sirius' eyes went wide. "You can't be serious."

"Well I'm not but you are." James said with a grin and Sirius couldn't help but let out another laugh this time groaning as it caused a pain to ache in his ribs, "He'd never agree to that."

"Won't know until we try. So how about it, shall we make a new deal?"

Sirius stared back at his best friend for a moment before a wide grin broke out over his face, "Definitely."

"Good, now I just need to figure out a way of breaking it off with Evans without upsetting Snape."

"Wait." Sirius started as he turned his head as far as it could go to face his friend, "How is this going to work anyway? Do I get him Monday through Wednesdays and you get him the rest or-"

Just then the door to the medical wing opened and both wizards froze as a lanky, pale dark haired boy slowly walked into the room. The two almost flushed as the Slytherin looked up at them with an arched brow as he stepped into the room, before letting out a snort.

"I see your skills in potion making are finally paying off."

Sirius couldn't help but growl at the comment, "Sod off, Snape."

Old habits die hard.

James bit back a sigh, while Severus just smirked as he walked further into the room and stopped to stand between their beds where they were levitating, "I have to say, I'm a little curious to know what it was that had depleted your attention span even more than usual. Some of the students seem to think that you were arguing over something. Trouble in paradise?"

Sirius paused as his flush got darker when James quickly spoke, "You sound worried Snape, is that why you came in here; to check up on us? I have to say I'm touched."

Snape sneered, "Don't flatter yourself Potter; I didn't come in here to grace myself with your presence."

"Then why are you here?"

The Slytherin opened his mouth to speak when another voice suddenly came from the bed on the other side of the room that had its curtains drawn.

"Severus?" a head of tawny blonde hair suddenly appeared behind the curtain and a very weak and sickly looking Remus appeared. Sirius' eyes went wide at the exact same time as James' when they suddenly remembered that the night before had been the night of the full moon and they totally missed it due to the accident.

The marauders were about to apologize to their friend when something so shocking happened that they were both rendered speechless.

"What do you think you're doing you stupid dog?" Snape hissed as he rushed over to Remus' side and caught him before he could stumble as he stepped forward carrying some of his weight as he pushed the curtains away with his free hand and helped Remus back into the bed. "You're ill; you shouldn't be out of bed right now."

"I heard your voice and I wanted to see you." Remus said with a tired smile as Severus put his feet up on the bed and pulled the sheets up over the wolf, "I missed you."

Snape did what James and Sirius used to think was impossible, when his cheeks suddenly flushed in a dark blush but still managed to glare as he eased the wolf back onto the bed, "For all you claims that you're not a dog you certainly behave like one."

Remus frowned, "Are you saying that you didn't miss me?"

Snape's blush went one shade darker and he just let out a frustrated sigh as he leaned down to press a lingering kiss on the werewolf's lips, "There, does that answer your question?"

A beaming smile broke out on Remus' face, "Not really, you should probably give me another just to be sure."

Severus rolled his eyes, "Honestly, you're just as insufferable as your friends."

"But you still love me more right?"

As the two continued James just stared at them at a complete loss for words until Sirius spoke, "Did-Did we lose to Moony?"

James didn't know what to say, until Severus went down to pick up Remus' tie which had fallen off the side table beside the bed when the werewolf suddenly looked up at his friends and gave them a wink and the hazel eyed wizard couldn't help but gape.

"That sneaky bastard."

Severus stood back up and Remus' face became the picture of innocence when the other sat down on the bed beside him.

"He really is just like us."

 **The End**

 **A/N:**

 **Please review.**


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